1. Field of the Invention
The present invention relates to a method and apparatus for interconnecting electrical conductors by use of electrical protuberances, such as raised bumps and rings.
2. Description of Related Art and Other Considerations
There are many techniques for obtaining interconnections among printed wiring boards, and ceramic and silicon wafers. Connectors, which are soldered and aligned to mating connectors, are very expensive. Hand wiring and soldering do not result in cost savings and the high density connections which are increasingly desired in the industry.
Bumps or projecting metallic contacts, as an alternate to soldered and alignable connectors, are known techniques for interconnecting flexible to flexible circuits, flexible to rigid printed circuits, or such circuits to electric components. Examples utilizing such bumps are described in U.S. Pat. Nos. 4,125,310 and 4,453,795. These patents describe a plurality of generally resilient metallic raised projections. In the latter patent, a resilient backup arrangement is used to avoid overstressing and squashing of the resilient contacts or projections beyond their elastic limit, which overstressing precludes repeated mating and unmating of connectors. These terminations otherwise effectively and reliably interconnect mating circuits, but their manufacture can be difficult, time consuming and costly. Many times, repeated etching and plating operations are required. Special attention is often required to select special materials, methodology, tooling and artwork. Many techniques limit the size of the bumps and, therefore, the density of interconnection which is desired.
It is, therefore, desirable to avoid these problems.